This proposal is concerned primarily with the perception of warmth, cold, odor, and nasal pungency (common chemical sensation) in the elderly. The main issue at stake is whether old age weakens everyday sensation levels in these domains and thereby may help to account for the common complaints in the aged about the flatness of food and impaired body temperature regulation. An improved psychophysical procedure, called magnitude matching, will be applied to the extensive testing of a group of elderly subjects (65-75 yrs) and to a control group (18-28 yrs). In this procedure, already examined here in pilot studies, subjects will make magnitude estimates of various levels of warmth, cold, odor, pungency, loudness, and length, interspersed in a test session and estimated on a common scale of sensory magnitude. The estimates can be treated in such a way as to generate for each group and for each subject some 30 cross-modality matching functions that relate the physical values of the stimuli that appear equal in sensory magnitude. Loudness and length are included as "yardstick" continua. This procedure uses a subject as his or her own control, thereby reducing potential biases associated with cognitive variables, population sampling errors, and individual idiosyncrasies in the use of numbers to represent sensory magnitudes. The procedure is sensitive enough to detect sensory losses in individual subjects, and subjects suspected of impairment will undergo repeated testing of magnitude, together with threshold measurements, to establish the psychophysical profile of the disorder.